1. Field of the Invention
The present invention relates to a device of a continuous, gravimetric metering and pneumatic conveyance of portable material wherein a material stream is conveyed by a conveying device over a measuring path while charging a load measuring device and the product of momentary load and conveying speed is identified.
2. Description of the Prior Art
Devices for continuous, gravimetric metering of pourable material are known in the art, for example, as metering conveyor type weighers. These are essentially employed for the formation of a constant-weight material stream in systems for the formation of mechanical mixtures or, respectively, for the gravimetric identification of a conveying capacity in, for example, loading or unloading a container of a vehicle.
A conveyor-type weigher can be employed either velocity-controlled or weight-controlled in order to produce a constant-weight material stream, for example, the formation of a constant mechanical mixture from a plurality of components. In this context, see Betriebshutte, 6th Edition, Vol. III, pp. 237-246.
Other devices, in addition to metering conveyor-type weighers, are known for the continuous, gravimetric metering of portable material, for example, belt conveyors, as well as continuously integrating bucket conveyor scales. A weight-controlled metering screw is likewise known in the art. The use of the metering screw is preferably reserved for the gravimetric conveying and/or metering of powdery material.
Metering conveyor-type weighers, due to the open structure of the conveying device, are only conditionally suitable for use with powdery, nearly free-flowing material. The formation of dust during delivery and/or discharge cannot be avoided even with careful boxing. Moreover, a metering conveyor-type weigher cannot be directly integrated in a pneumatic conveying device for powdery material. Similar disadvantages also apply to other known metering conveyor systems such as, for example, belt conveyors and/or metering screws. As a consequence, these known gravimetric metering devices are not suitable for charging with, for example, combustible, toxic, powdery substances subject to oxidation serving for the production of foodstuffs which are sensitive for material reasons.
Devices for continuous, gravimetric metering of fine-grain material which can also be directly and without problems inserted in a pneumatic conveying system at the same time are unknown in the art.